The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
Transflective LCDs may be used in cell phones, electronic books, and personal computers in part because readability of transflective LCDs typically is not limited by ambient lighting conditions. A transflective LCD comprises an array of pixels each having a reflective part and a transmissive part. In the reflective part of a transflective LCD pixel, there may be a metal reflector over a thin film transistor unit. In transflective LCDs that use a relatively small metal reflector in a pixel, while enough backlight may be able to transmit through the pixel, not enough ambient light is reflected to show the pixel at a desired luminance.
On the other hand, in some transflective LCDs that use a relatively large metal reflector in a pixel, while enough ambient light may be reflected, not enough backlight is able to transmit through the pixel. For instance, a circularly polarized backlight may be blocked by the relatively large metal reflector in the reflective part and cannot be efficiently redirected into the transmissive part. This significantly lowers the optical output efficiency of the backlight units (BLUs), and reduces overall light transmittance and brightness in pixels of the transflective LCDs. The problem becomes especially severe when the area of the reflective part is comparable to or larger than that of the transmissive part in the pixel.
The drawings are not rendered to scale.